Waste system for toilets

ABSTRACT

A process and apparatus to implement the process for the disposal of toilet waste in a relatively small space with low input energy. The process to include the following operations: separating the liquid portion from the solid portion of the toilet waste, disposing of the liquid portion of the waste by drainage, forming a mixture by combining the solid portion of the waste with a quantity of flammable material having structural properties that retain air passages within the mixture, storing the mixture in a chamber, and burning the mixture within the chamber.

TECHNICAL FIELD

This invention relates to an improved method of waste disposal to beused with toilets that cannot be connected to sewer drains andparticularly to be used with dry toilets with disposable bowl liningmaterial.

BACKGROUND

Worldwide water shortages and the expense of cleaning up polluted waterhas resulted in an increasing need to dispose of toilet waste withoutthe use of water or centralised sewage processing.

Toilets which do not use water and which do not depend on central sewageprocessing fall into four types--incinerating toilets, sterling toilets,composting toilets and lined toilets. Incinerating toilets use anexternal source of energy to heat the waste, evaporate all the liquidwaste and burn the remaining solid waste. Disadvantages are the highinitial cost, the high operating cost and the use restriction imposed bythe incinerating cycles. Similarly, sterilizing toilets use externalenergy to evaporate urine and heat the feces to kill the bacteria butrequire the inconvenience of frequent manual clean out for disposalelsewhere. Composting toilets store the waste in an aerated chamber anduse aerobic bacteria to digest or oxidise the waste over a long timeperiod. Composting toilets are bulky and relatively expensiveinstallations which need frequent manual attention. Lined toiletssurround the waste in plastic and transport it to a storage containerfor eventual manual removal and separate disposal elsewhere.

None of the foregoing waterless toilets perform their function asconveniently and with as little user attention as a conventional waterflushing toilet. However, the water flushing toilet does not have toactually dispose of the waste. It uses clean water to move the waste toa remote location where more expensive disposal processes areundertaken. In many parts of the world this is no longer an economicallyviable procedure.

Most toilets which combine solid and liquid waste together cannot takeadvantage of the fact that liquid toilet waste containing urine and anyflushing water is much easier to dispose of than solid toilet wastecontaining feces, paper, diapers, fibrous sanitary items and potentiallyharmful pathogens. Urine which is normally sterile and constitutes thebulk of human waste is readily absorbed into soil or dispersed inwaterways without environmental harm whereas solid toilet waste requiresspecial treatment before it can be released into the environment.

To eliminate a health hazard it would be better to incinerate the solidtoilet waste but the high water content and the low heating value of thewaste makes this expensive and complicated.

DISCLOSURE OF INVENTION

The cost and inconvenience of disposing of toilet waste at the toiletsite can be greatly improved by the present invention which isapplicable to dry toilets, particularly dry toilets using disposablebowl lining sheet, and which provides means by which all the solidtoilet waste can be incinerated economically with minimal use ofexternal energy.

The present invention is a process which includes the followingoperations:

1) Separating the liquid portion of the toilet waste from the solidportion of the toilet waste,

2) Disposing of the liquid portion of the waste by drainage,

3) Forming a mixture by combining the solid portion with a quantity offlammable material with structural properties that retain air passageswithin the mixture,

4) Storing the mixture in a chamber, and

5) Burning the mixture within the chamber.

This process can eliminate or substantially reduces the amount ofexternal energy that would normally be required to incinerate toiletwaste and can be implemented by apparatus of relatively smallproportions which would be suitable for installation in residentialpremises.

Although it is technically feasible to apply this process to aconventional incinerating toilet, an example of which is disclosed byFrankel et al. in U.S. Pat. No. 4,138,331, extensive modification wouldbe required to drain the liquid waste, to provide a supply of flammableaerating material (eg. plastic shapes), to mix the flammable aeratingmaterial with the solid waste and to store the mixture in a separatechamber. The amount of fuel saved might not justify the extra cost ofthe apparatus and the added flammable material.

The process becomes more commercially viable when applied to a dryflushing toilet employing bowl lining material such as is described inInternational Publication Number WO95/24853. This type of toilet has abowl lined with thin sheet material which is renewed each time thetoilet is used. The sheet material could be polyethylene which burnseasily and has a heat value of 46,500 kilojoules per kilogram. Thisvalue is greater than coal or fuel oil and is three times higher thandry feces or paper. The referenced toilet is described as having bowlwith a sloped bottom surface to assist the separation of liquid wastefrom the solid waste within the bowl lining sheet. The bowl lining sheetis shown as a substantially continuous rectangular sheet which isunsealed at the exit aperture on the side of the bowl and would, unlessotherwise obstructed, allow the liquid portion of the waste to flow outof the bowl.

To further implement the operation to separate the liquid waste adrainage channel is provided which leads to a lower chamber adapted toreceive and to dispose of the liquid waste and having an entrance waywith a screen or particle filter through which the solid waste cannotpass. To implement an operation to form a burnable mixture composed offlammable liner sheet and solid toilet waste a pump housing is providedto receive the soiled liner sheet and any solid toilet waste as they areremoved or flushed from the bowl by the dry toilet's liner sheetconveyance mechanism. The pump housing is equipped with a piston with acutter which when advanced through the pump housing crumples and cutsthe liner sheet to form a wad. This action spreads the solid wasteagainst the surface of the sheet while at the same time making airpassages between the folds of the sheet which assist the further dryingand subsequent burning of the mixture. The motion of the piston alsopushes the wad into a waste pipe leading to a solid waste storagechamber.

Subsequent flushing cycles result in the accumulation of wads within thestorage chamber. To assist the further drying and the successive burningof the waste provision can be made for the storage chamber walls to beventilated and to be surrounded by a duct connected to a chimney throughwhich drying air can flow to the outside atmosphere. The accumulatedwaste in the ventilated storage chamber gets drier as time progressesthus further improving combustion efficiency. Burning of the wastemixture within the storage chamber can be initiated by electric or gasigniters. Ordinarily the polyethylene content would provide the higherheat value necessary to sustain combustion in the presence of moistsolid waste, however, in cold damp conditions a supplemental heat sourcecould ensure more complete combustion. Alternatively, the storagechamber could be manufactured from a disposable and burnable materialwith provision for detaching from the inlet duct for incineration at aremote facility.

It is normal for moist toilet waste to biologically decompose. In theabsence of air anaerobic bacteria will release unpleasantly smellinggases that will be undesirable even if vented to the outside atmosphere.However, the air passages created by the crumpled liner material or anyother aerating additive would encourage digestion by aerobic bacteriathe products of which are not objectionable. As drying decreases themoisture content, the biological activity will also decrease.

The liquid waste that drains into the lower chamber is mostly urinewhich is normally a sterile liquid containing harmless compounds andsalts but it could be contaminated by bacteria from the feces. Urinewould normally be discharged without treatment into a sewer drain or drywell but if the circumstances require it could be sterilized bychemicals or by ultra violet radiation before discharge.

Without a connection to an outside vent or a liquid drain it is notpractical for portable toilets to dispose of the waste in situ.Nevertheless, the essential processes of this invention, i.e. separationof liquid and solid waste, adding aerating material, draining anddrying, can be accomplished but only over a shorter period due tolimited storage space. The resulting waste would have a relativelyhigher moisture content but would with the added heat value stillincinerate well in the presence of other combustibles. Furthermore, thewaste holding unit could be made of polyethylene which would be disposedof or burned along with the contained solid waste thus minimisingunpleasant handling. The liquid would be drained from its portion of thedisposable waste holding unit before incineration.

A preferred form of apparatus to implement the waste disposal process ofthis invention would comprise: a dry flushing toilet which uses bowllining sheet material to contain the toilet waste and to convey thewaste out of the bowl, the sheet material being combustible and ofrelatively high heat value, an opening in the sheet material throughwhich liquid waste can drain while the solid waste is retained, a pumphousing adapted to receive the soiled bowl liner sheet together with anysolid toilet waste when they are conveyed out of the bowl, a pistonwithin the pump housing equipped with a cutting device which whenadvanced crumples and cuts the soiled liner sheet to form a wad with airpassages between the folds of the liner sheet, an upper chamber for thestorage of the soiled liner sheet and the solid waste, a pipe connectingto the pump housing through which the wads produced by the piston can betransported for storage in the upper chamber, the upper chamber havingmeans for the passage of air through the chamber, a lower chamberadapted to receive the liquid waste that has drained out of the linersheet, the lower chamber having means for draining the liquid waste, aparticle filter interposed between the internal volume of the upperchamber and the internal volume of the lower chamber, the filter beingdimensioned to allow the passage of the liquid waste into the lowerchamber and to contain the solid waste in the upper chamber, and a meansfor igniting and burning the waste within the upper chamber.

In another preferred form of apparatus to implement this waste disposalprocess, the upper and lower chambers, the particle filter and theconnection to the toilet pump housing can be fabricated in one piecefrom a thin, flexible and combustible material which when manufacturedwill lie flat but when in use will expand to contain the incoming toiletwaste. This disposable waste holding unit can also be provided with alowermost spout with an openable seal to assist the removal of theliquid waste before incineration, an upper vent with an integralchemical filter to prevent the escape of odorous chemicals whileallowing the ingress of air and a soluble chemical biocide packaged intothe lower liquid portion to maintain sterile conditions.

BRIEF DESCRIPTION OF DRAWINGS

This invention will be further described by way of example only, byreference to the accompanying and purely diagrammatic drawings, inwhich:

FIG. 1 is a side view of a lined, dry toilet exposing a section throughthe waste pump with the piston in the closed position;

FIG. 2 is as FIG. 1 but with the piston partly retracted;

FIG. 3 is as FIG. 1 but with the piston fully retracted;

FIG. 4 is section view of the side of the waste holding incineratorchamber;

FIG. 5 is a side view of a lined, dry toilet exposing a section throughthe waste pump and an attached disposable waste holding unit;

FIG. 6 is as FIG. 5 but showing a method of removing the disposablewaste holding unit;

FIG. 7 is an end section view of the disposable waste container holdingunit; and

FIG. 8 is an end section view showing a disposable waste holding unit ofan alternative type of construction.

BEST MODE FOR CARRYING OUT INVENTION

A lined toilet shown in FIG. 1 has a bowl 15 which is lined withflammable plastic sheet 16 which is shown emerging from the bowl's exitaperture 17 and entering into a pump housing 18 where the end of theplastic sheet 16 is pinched closed by the pressure of a piston 19against an opposing surface on the pump housing 18. When the toilet isused a slope at the bottom of the bowl 15 and a slope at bottom of theexit aperture 17 cause liquid waste to drain down and accumulate in theplastic sheet 16 near the piston 19 whereas solid waste which does notflow readily is retained in another part of the plastic sheet 16 in thecenter of the bowl 15. In FIG. 2 the flushing cycle has started and thepiston 19 has partly retracted thus releasing the pinched end of theplastic sheet 16 and allowing any accumulated liquid waste to drain intothe bottom of the pump housing 18 where the it can flow along the bottomof a waste pipe 20. FIG. 3 shows the piston 19 fully retracted thusleaving the pump housing 18 open to receive the soiled plastic sheet 16containing any solid toilet waste that may have been deposited in thebowl 15 but without the liquid waste which has already drained fromwithin the plastic sheet 16. To complete the flushing cycle the piston19 is advanced to close the open pump housing 18 and force the soiledplastic sheet 16 containing the solid waste into the drain pipe 20 andsimultaneously forcing the waste from previous flushing cycles furtheralong the waste pipe 20. As the piston 19 reaches the end of its advancea clean portion of the plastic sheet 16 is again pinched closed andsimultaneously a cutter 21 at the end of the piston severs the soiledportion of the plastic sheet 16 from the clean portion which makes a newopening through which liquid waste can drain during the next flushingcycle. The force of the piston 19 acting on the soiled liner sheet 16which has been deposited in the pump housing 18 spreads any solid wastecontained therein against the surface of the sheet 16 and simultaneouslyfolds and crumples the sheet 16, thus creating air passages between thefolds to facilitate the subsequent drying and burning of the mixture.

Now referring to FIG. 4 the waste pipe 20 extends from the end of thepump housing 18 over a particle filter 22 through which the liquid wastedrains into a lower chamber 23 and from there through an optionalsterilizing device 24 before entering the discharge pipe 25. The plasticsheet 16 containing the solid waste is progressively pushed along thedrain pipe 20 which bends upward into a solid waste storage chamber 26.The upper portion of the chamber walls 27 are made of metal mesh whichexposes the waste sheet material 16 to the air within a duct 28 whichsurrounds the solid waste chamber 26. Air enters the duct 28 throughlower ports 29 and passes out the top through a chimney 30 to theoutside atmosphere. The waste material within the chamber 26 getsprogressively drier the longer it is stored. When dry enough to supportcombustion the waste sheet material 16 can be ignited manually through aport 31 in the duct or it could be ignited automatically by an igniterdevice 32 triggered by a sensor. The waste sheet material 16 togetherwith the solid waste will burn within the storage chamber 26 untilextinguished by excessive moisture content or until air is excluded bythe air tight walls 33 on the lower portion of the container 26.Combustion gases pass up through the chimney 30 and any residual ashwhich falls out through the container walls 27 can collect on the bottomof the duct 28 and be removed through a clean-out door 34.

A lined toilet intended for portable use is shown in FIGS. 5 & 6 wherethe pump housing 18 is connected directly to a disposable waste holdingunit 35 which is divided into an upper storage chamber 36 to contain thesoiled sheet material 16 together with the solid waste and a lowerstorage chamber 37 to contain the liquid waste. The upper storagechamber 36 is separated from the lower storage chamber 37 by a particlefilter 38 which allows only the essentially liquid waste to pass intothe lower storage chamber 37. The disposable waste holding unit 35 isconnected to the pump housing 18 by means of an extendable sleeve 39which is clamped around the outside of the pump housing 18. The weightof the waste holding unit 35 is supported on bracket 43 which couldextend as shown in FIG. 6 to facilitate removal of the extendable sleeve39 from the pump housing 18 by providing room to apply a tie 44 to thesleeve 39 thus sealing the waste holding unit 35 before disconnectingfrom the pump housing 18.

The handle 45 facilitates the manual lifting of the waste holding unit35 for disposal elsewhere. Before disposal by incineration the liquidwaste can be drained from the lower storage chamber 37 by opening asealed spout 46. The lower storage chamber 37 can also contain a biocidechemical which will keep the accumulated liquid waste 48 sterile. Theupper storage chamber 36 may be provided with an air vent 47 into whichis sealed a filter to prevent the escape of smells or contaminatedparticles. The air vent 47 could assist the disposal of the wasteholding unit 35 by allowing its volume to be reduce by squeezing andwould also discourage odor producing anaerobic bacteria.

The disposable container 35 can be manufactured from flat thermoplasticsheets the seams of which are heat sealed together to form the storagechambers 36 and 37 and the sleeve 39 as well as the small passages thatform particle filter 38. The flat plastic will expand in use to containthe waste as shown in cross section in FIG. 7. Alternatively, as shownin FIG. 8, the particle filter 38 could be provided in the form of atextile sheet 49 also heat sealed into the waste holding unit 35. Thetextile sheet particle filter 49 has more surface area than thethermoformed particle filter 38 and would be less likely to becomeclogged.

We claim:
 1. A process for disposal of toilet waste having a liquidportion and a solid portion, the process to include the followingoperations: separating the liquid portion from the solid portion of thewaste, disposing of the liquid portion of the waste by drainage, forminga mixture by combining the solid portion with a quantity of flammablematerial with structural properties that retain air passages within themixture, storing the mixture in a chamber, and burning the mixturewithin the chamber.
 2. A process for disposal of toilet waste accordingto claim 1 wherein the flammable material is in the form of a sheetmaterial wrapper which partly surrounds the toilet waste, the wrapperhaving an opening through which the liquid portion of the waste candrain away while the solid portion is retained.
 3. Apparatus fordisposal of toilet waste to implement the process of claims 1 or 2comprising; combustible sheet material capable of being formed into acontainer for holding toilet waste, a storage unit having an upperchamber and a lower chamber divided by a wall, the wall havingperforations through which the liquid waste can drain into the lowerchamber while the solid waste is retained in the upper chamber, anopening in the upper chamber adapted to receive the toilet waste,transporting means to move the sheet material containing toilet wastethrough the opening into the upper chamber and means for draining theliquid waste out of the lower chamber.
 4. Apparatus for disposal oftoilet waste according to claim 3 wherein the storage unit is adapted bymeans of vents for the combustion of the solid waste within the upperchamber.
 5. Apparatus for disposal of toilet waste according to claim 3wherein the storage unit is formed from combustible material and hasmeans for detaching from the transporting apparatus for disposal byburning.
 6. Apparatus for disposal of toilet waste according to claim 3wherein there is provided a cutter to slit the sheet material to assistthe liquid waste to drain out of the the container formed by the sheetmaterial.